What changed when twins tried different diets?
In an eight-week comparison, a healthy vegan diet lowered LDL cholesterol more than a healthy omnivorous diet.
The 30-second takeaway
One twin in each pair tried a healthy vegan diet; the other tried a healthy omnivorous diet. After eight weeks, LDL cholesterol fell more with the vegan diet. The twin design helps account for genetics, but this was a comparison of whole diets, not proof that removing any single food caused the change.
A small, supported diet trial cannot establish lifelong outcomes or isolate the effect of removing animal foods.
What researchers found
Difference in LDL change
Vegan versus omnivorous diet at eight weeks; 95% confidence interval −25.3 to −2.4 mg/dL. A blood marker, not heart attacks.
Why use twins?
Identical twins share genetics, making them a useful comparison. Assignment within each pair was randomized; participants knew which diet they followed.
What changed together
The diets differed in multiple foods and overall intake. LDL was the primary outcome, while the trial was too short to measure long-term disease outcomes.
The original publication
Cardiometabolic Effects of Omnivorous vs Vegan Diets in Identical Twins: A Randomized Clinical Trial
Matthew J. Landry et al.
JAMA Network Open · 2023
- PubMed ID
- 38032644
- Record checked
Updates and discussion
2023 correction: secondary-outcome wording; primary LDL result unchanged ↗
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